Effects of pentoxifylline and nabumetone on the serum levels of IL-1β and TNFα in rats with adjuvant arthritis

Objective and Design: This study examined whether serum levels of cytokines, IL-1 beta and TNF alpha were elevated in rats with adjuvant arthritis in relation to disease progression, and if so, to verify the treatment effects of nabumetone (20 mg/kg, p.o.), a COX-2 inhibitor and pentoxifylline (20 mg/kg, p.o.), a type-4 phosphodiesterase (PDE4) inhibitor, alone or in combination.Materials and Methods: Female Wistar rats were used. Freund's complete adjuvant (FCA) was used to induce arthritis. The increment in contralateral hind paw volume (the secondary lesion) was determined by plethysmometry and the serum cytokines were measured by ELISA.Results: In control rats, the serum IL-1 beta and TNF alpha levels were greatly elevated on the very first day i.e. 5 h after FCA, and thereupon a progressive decrease in IL-1 beta but not TNF alpha was observed until day 30. The secondary arthritic lesion began to increase on day 14 (125 plus or minus 26 mu l), and attained its peak (330 plus or minus 79 mu l) on day 21 post-adjuvant injection. The peak arthritic lesion was significantly (p